From 16f7018af1f278a9f0cc368e224258860ea4cb8c Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Thu, 6 Dec 2018 23:26:24 +0000
Subject: deduplicate strings VM-wide in Ruby 2.5+

String#-@ deduplicates strings starting with Ruby 2.5.0
Hash#[]= deduplicates strings starting in Ruby 2.6.0-rc1

This allows us to save a small amount of memory by sharing
objects with other parts of the stack (e.g. Rack).
---
 ext/unicorn_http/extconf.rb | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

(limited to 'ext/unicorn_http/extconf.rb')

diff --git a/ext/unicorn_http/extconf.rb b/ext/unicorn_http/extconf.rb
index 2fc60fe..d5f81fb 100644
--- a/ext/unicorn_http/extconf.rb
+++ b/ext/unicorn_http/extconf.rb
@@ -8,4 +8,34 @@ have_func("rb_str_set_len", "ruby.h") or abort 'Ruby 1.9.3+ required'
 have_func("rb_hash_clear", "ruby.h") # Ruby 2.0+
 have_func("gmtime_r", "time.h")
 
+message('checking if String#-@ (str_uminus) dedupes... ')
+begin
+  a = -(%w(t e s t).join)
+  b = -(%w(t e s t).join)
+  if a.equal?(b)
+    $CPPFLAGS += ' -DSTR_UMINUS_DEDUPE=1 '
+    message("yes\n")
+  else
+    $CPPFLAGS += ' -DSTR_UMINUS_DEDUPE=0 '
+    message("no, needs Ruby 2.5+\n")
+  end
+rescue NoMethodError
+  $CPPFLAGS += ' -DSTR_UMINUS_DEDUPE=0 '
+  message("no, String#-@ not available\n")
+end
+
+message('checking if Hash#[]= (rb_hash_aset) dedupes... ')
+h = {}
+x = {}
+r = rand.to_s
+h[%W(#{r}).join('')] = :foo
+x[%W(#{r}).join('')] = :foo
+if x.keys[0].equal?(h.keys[0])
+  $CPPFLAGS += ' -DHASH_ASET_DEDUPE=1 '
+  message("yes\n")
+else
+  $CPPFLAGS += ' -DHASH_ASET_DEDUPE=0 '
+  message("no, needs Ruby 2.6+\n")
+end
+
 create_makefile("unicorn_http")
-- 
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